1. Field
The present teachings relate to RF (radio frequency) circuits. More particularly, the present teachings relate to methods and apparatuses for reducing impact of hot carrier injection in transistors of an RF amplifier when the transistors are subjected to high stress.
2. Description of Related Art
Radio frequency (RF) amplifiers are a main component of an RF device, such as cell phone, and can define a performance of the RF device in terms of power output and linearity of a transmitted RF signal. In order to keep an RF amplifier performance optimal, as measured for example by some characteristics of the transmitted RF signal, such as linearity, harmonic composition and efficiency, careful design of a corresponding biasing circuitry is necessary. A biasing circuitry however operates on a known input/output characteristic of the RF amplifier at the time of assembly (e.g. production testing) and does not take into account variations due to aging of the various elementary components (e.g. transistors) of the RF amplifier. The teachings according to the present disclosure provide a solution to the drift in biasing of an RF amplifier due to aging of its constituent transistors.